Gas turbine engines mainly comprise a compressor section, a combustor section, and a turbine section. The turbine section itself again is comprised of a plurality of turbine stages. Each turbine stage consists of a set of guide vanes followed by a set of rotor blades. The guide vanes and the rotor blade experience high temperatures during operation and therefore are manufactured from high temperature resistant material and/or require cooling features to withstand the high temperatures. A complete ring of guide vanes typically consists of a plurality of guide vane segments. Such a segment typically comprises at least a platform and at least one airfoil.
Such guide vane segments are typically cast elements that are manufactured by known manufacturing techniques. Casting is a manufacturing process in which moulds are filled with liquid materials that are subsequently solidified. In such a casting process there is a limitation in geometry and in providing cooling features, as not all possible configurations can be produced.
Casting of guide vane segments can be very expensive if a lot of material is needed to build the guide vane segment. To reduce the costs typically that material is selected that is perfectly adapted for the to be expected temperatures.
One casting technique which is typically more expensive than “normal” casting is the so called precision casting.
From EP 1 731 715 A1 it is known that a gap may be present between a downstream end of a combustor and consecutive turbine section. This gap may be closed via a cover as a further separate component. According to a figure in this document the cover may follow the form of a segment of a cylinder.
EP 2 428 647 A1 also focuses on a transition area between a combustor and a turbine section. A heat shield will be placed as a boundary surface for the flow path.
FR 3 003 599 A1 relates to a vane with an annular platform, the vane being characterized in that an inner ring comprises a first annular plate attached to a radial wall, said plate including an end annular strip folded to bear against a radial annular wall. The strip is adjacent to the back surface of the annular platform.
Referring back to the cooling features of guide vane segments, besides providing cooling cavities and cooling holes in the guide vane segment, it could be an alternative to provide cooling features from an adjacent component like the exit of the compressor or to provide additional stator or rotor components that allow cooling air to impinge onto a surface of the guide vane segment.